/*
 * Copyright 2002-2017 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.beans.factory.support;

import java.lang.reflect.AnnotatedElement;
import java.lang.reflect.Executable;
import java.lang.reflect.Member;
import java.lang.reflect.Method;
import java.util.HashSet;
import java.util.Set;
import java.util.function.Supplier;

import org.springframework.beans.MutablePropertyValues;
import org.springframework.beans.factory.config.BeanDefinition;
import org.springframework.beans.factory.config.BeanDefinitionHolder;
import org.springframework.beans.factory.config.ConstructorArgumentValues;
import org.springframework.core.ResolvableType;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;

/**
 * A root bean definition represents the merged bean definition that backs
 * a specific bean in a Spring BeanFactory at runtime. It might have been created
 * from multiple original bean definitions that inherit from each other,
 * typically registered as {@link GenericBeanDefinition GenericBeanDefinitions}.
 * A root bean definition is essentially the 'unified' bean definition view at runtime.
 *
 * <p>Root bean definitions may also be used for registering individual bean definitions
 * in the configuration phase. However, since Spring 2.5, the preferred way to register
 * bean definitions programmatically is the {@link GenericBeanDefinition} class.
 * GenericBeanDefinition has the advantage that it allows to dynamically define
 * parent dependencies, not 'hard-coding' the role as a root bean definition.
 *
 * @author Rod Johnson
 * @author Juergen Hoeller
 * @see GenericBeanDefinition
 * @see ChildBeanDefinition
 */
@SuppressWarnings("serial")
public class RootBeanDefinition extends AbstractBeanDefinition {

    /**
     * Common lock for the four constructor fields below
     */
    final Object constructorArgumentLock = new Object();
    /**
     * Common lock for the two post-processing fields below
     */
    final Object postProcessingLock = new Object();
    boolean allowCaching = true;

    boolean isFactoryMethodUnique = false;

    @Nullable
    volatile ResolvableType targetType;

    /**
     * Package-visible field for caching the determined Class of a given bean definition
     */
    @Nullable
    volatile Class<?> resolvedTargetType;

    /**
     * Package-visible field for caching the return type of a generically typed factory method
     */
    @Nullable
    volatile ResolvableType factoryMethodReturnType;
    /**
     * Package-visible field for caching the resolved constructor or factory method
     */
    @Nullable
    Executable resolvedConstructorOrFactoryMethod;
    /**
     * Package-visible field that marks the constructor arguments as resolved
     */
    boolean constructorArgumentsResolved = false;
    /**
     * Package-visible field for caching fully resolved constructor arguments
     */
    @Nullable
    Object[] resolvedConstructorArguments;
    /**
     * Package-visible field for caching partly prepared constructor arguments
     */
    @Nullable
    Object[] preparedConstructorArguments;
    /**
     * Package-visible field that indicates MergedBeanDefinitionPostProcessor having been applied
     */
    boolean postProcessed = false;
    /**
     * Package-visible field that indicates a before-instantiation post-processor having kicked in
     */
    @Nullable
    volatile Boolean beforeInstantiationResolved;
    @Nullable
    private BeanDefinitionHolder decoratedDefinition;
    @Nullable
    private AnnotatedElement qualifiedElement;
    @Nullable
    private Set<Member> externallyManagedConfigMembers;

    @Nullable
    private Set<String> externallyManagedInitMethods;

    @Nullable
    private Set<String> externallyManagedDestroyMethods;


    /**
     * Create a new RootBeanDefinition, to be configured through its bean
     * properties and configuration methods.
     *
     * @see #setBeanClass
     * @see #setScope
     * @see #setConstructorArgumentValues
     * @see #setPropertyValues
     */
    public RootBeanDefinition() {
        super();
    }

    /**
     * Create a new RootBeanDefinition for a singleton.
     *
     * @param beanClass the class of the bean to instantiate
     * @see #setBeanClass
     */
    public RootBeanDefinition(@Nullable Class<?> beanClass) {
        super();
        setBeanClass(beanClass);
    }

    /**
     * Create a new RootBeanDefinition for a singleton bean, constructing each instance
     * through calling the given supplier (possibly a lambda or method reference).
     *
     * @param beanClass the class of the bean to instantiate
     * @param instanceSupplier the supplier to construct a bean instance,
     * as an alternative to a declaratively specified factory method
     * @see #setInstanceSupplier
     * @since 5.0
     */
    public <T> RootBeanDefinition(@Nullable Class<T> beanClass, @Nullable Supplier<T> instanceSupplier) {
        super();
        setBeanClass(beanClass);
        setInstanceSupplier(instanceSupplier);
    }

    /**
     * Create a new RootBeanDefinition for a scoped bean, constructing each instance
     * through calling the given supplier (possibly a lambda or method reference).
     *
     * @param beanClass the class of the bean to instantiate
     * @param scope the name of the corresponding scope
     * @param instanceSupplier the supplier to construct a bean instance,
     * as an alternative to a declaratively specified factory method
     * @see #setInstanceSupplier
     * @since 5.0
     */
    public <T> RootBeanDefinition(@Nullable Class<T> beanClass, String scope, @Nullable Supplier<T> instanceSupplier) {
        super();
        setBeanClass(beanClass);
        setScope(scope);
        setInstanceSupplier(instanceSupplier);
    }

    /**
     * Create a new RootBeanDefinition for a singleton,
     * using the given autowire mode.
     *
     * @param beanClass the class of the bean to instantiate
     * @param autowireMode by name or type, using the constants in this interface
     * @param dependencyCheck whether to perform a dependency check for objects
     * (not applicable to autowiring a constructor, thus ignored there)
     */
    public RootBeanDefinition(@Nullable Class<?> beanClass, int autowireMode, boolean dependencyCheck) {
        super();
        setBeanClass(beanClass);
        setAutowireMode(autowireMode);
        if (dependencyCheck && getResolvedAutowireMode() != AUTOWIRE_CONSTRUCTOR) {
            setDependencyCheck(DEPENDENCY_CHECK_OBJECTS);
        }
    }

    /**
     * Create a new RootBeanDefinition for a singleton,
     * providing constructor arguments and property values.
     *
     * @param beanClass the class of the bean to instantiate
     * @param cargs the constructor argument values to apply
     * @param pvs the property values to apply
     */
    public RootBeanDefinition(@Nullable Class<?> beanClass, @Nullable ConstructorArgumentValues cargs,
            @Nullable MutablePropertyValues pvs) {

        super(cargs, pvs);
        setBeanClass(beanClass);
    }

    /**
     * Create a new RootBeanDefinition for a singleton,
     * providing constructor arguments and property values.
     * <p>Takes a bean class name to avoid eager loading of the bean class.
     *
     * @param beanClassName the name of the class to instantiate
     */
    public RootBeanDefinition(String beanClassName) {
        setBeanClassName(beanClassName);
    }

    /**
     * Create a new RootBeanDefinition for a singleton,
     * providing constructor arguments and property values.
     * <p>Takes a bean class name to avoid eager loading of the bean class.
     *
     * @param beanClassName the name of the class to instantiate
     * @param cargs the constructor argument values to apply
     * @param pvs the property values to apply
     */
    public RootBeanDefinition(String beanClassName, ConstructorArgumentValues cargs, MutablePropertyValues pvs) {
        super(cargs, pvs);
        setBeanClassName(beanClassName);
    }

    /**
     * Create a new RootBeanDefinition as deep copy of the given
     * bean definition.
     *
     * @param original the original bean definition to copy from
     */
    public RootBeanDefinition(RootBeanDefinition original) {
        super(original);
        this.decoratedDefinition = original.decoratedDefinition;
        this.qualifiedElement = original.qualifiedElement;
        this.allowCaching = original.allowCaching;
        this.isFactoryMethodUnique = original.isFactoryMethodUnique;
        this.targetType = original.targetType;
    }

    /**
     * Create a new RootBeanDefinition as deep copy of the given
     * bean definition.
     *
     * @param original the original bean definition to copy from
     */
    RootBeanDefinition(BeanDefinition original) {
        super(original);
    }


    @Override
    public String getParentName() {
        return null;
    }

    @Override
    public void setParentName(@Nullable String parentName) {
        if (parentName != null) {
            throw new IllegalArgumentException("Root bean cannot be changed into a child bean with parent reference");
        }
    }

    /**
     * Return the target definition that is being decorated by this bean definition, if any.
     */
    @Nullable
    public BeanDefinitionHolder getDecoratedDefinition() {
        return this.decoratedDefinition;
    }

    /**
     * Register a target definition that is being decorated by this bean definition.
     */
    public void setDecoratedDefinition(@Nullable BeanDefinitionHolder decoratedDefinition) {
        this.decoratedDefinition = decoratedDefinition;
    }

    /**
     * Return the {@link AnnotatedElement} defining qualifiers, if any.
     * Otherwise, the factory method and target class will be checked.
     *
     * @since 4.3.3
     */
    @Nullable
    public AnnotatedElement getQualifiedElement() {
        return this.qualifiedElement;
    }

    /**
     * Specify the {@link AnnotatedElement} defining qualifiers,
     * to be used instead of the target class or factory method.
     *
     * @see #setTargetType(ResolvableType)
     * @see #getResolvedFactoryMethod()
     * @since 4.3.3
     */
    public void setQualifiedElement(@Nullable AnnotatedElement qualifiedElement) {
        this.qualifiedElement = qualifiedElement;
    }

    /**
     * Return the target type of this bean definition, if known
     * (either specified in advance or resolved on first instantiation).
     *
     * @since 3.2.2
     */
    @Nullable
    public Class<?> getTargetType() {
        if (this.resolvedTargetType != null) {
            return this.resolvedTargetType;
        }
        ResolvableType targetType = this.targetType;
        return (targetType != null ? targetType.resolve() : null);
    }

    /**
     * Specify a generics-containing target type of this bean definition, if known in advance.
     *
     * @since 4.3.3
     */
    public void setTargetType(ResolvableType targetType) {
        this.targetType = targetType;
    }

    /**
     * Specify the target type of this bean definition, if known in advance.
     *
     * @since 3.2.2
     */
    public void setTargetType(@Nullable Class<?> targetType) {
        this.targetType = (targetType != null ? ResolvableType.forClass(targetType) : null);
    }

    /**
     * Specify a factory method name that refers to a non-overloaded method.
     */
    public void setUniqueFactoryMethodName(String name) {
        Assert.hasText(name, "Factory method name must not be empty");
        setFactoryMethodName(name);
        this.isFactoryMethodUnique = true;
    }

    /**
     * Check whether the given candidate qualifies as a factory method.
     */
    public boolean isFactoryMethod(Method candidate) {
        return candidate.getName().equals(getFactoryMethodName());
    }

    /**
     * Return the resolved factory method as a Java Method object, if available.
     *
     * @return the factory method, or {@code null} if not found or not resolved yet
     */
    @Nullable
    public Method getResolvedFactoryMethod() {
        synchronized (this.constructorArgumentLock) {
            Executable candidate = this.resolvedConstructorOrFactoryMethod;
            return (candidate instanceof Method ? (Method) candidate : null);
        }
    }

    public void registerExternallyManagedConfigMember(Member configMember) {
        synchronized (this.postProcessingLock) {
            if (this.externallyManagedConfigMembers == null) {
                this.externallyManagedConfigMembers = new HashSet<>(1);
            }
            this.externallyManagedConfigMembers.add(configMember);
        }
    }

    public boolean isExternallyManagedConfigMember(Member configMember) {
        synchronized (this.postProcessingLock) {
            return (this.externallyManagedConfigMembers != null &&
                    this.externallyManagedConfigMembers.contains(configMember));
        }
    }

    public void registerExternallyManagedInitMethod(String initMethod) {
        synchronized (this.postProcessingLock) {
            if (this.externallyManagedInitMethods == null) {
                this.externallyManagedInitMethods = new HashSet<>(1);
            }
            this.externallyManagedInitMethods.add(initMethod);
        }
    }

    public boolean isExternallyManagedInitMethod(String initMethod) {
        synchronized (this.postProcessingLock) {
            return (this.externallyManagedInitMethods != null &&
                    this.externallyManagedInitMethods.contains(initMethod));
        }
    }

    public void registerExternallyManagedDestroyMethod(String destroyMethod) {
        synchronized (this.postProcessingLock) {
            if (this.externallyManagedDestroyMethods == null) {
                this.externallyManagedDestroyMethods = new HashSet<>(1);
            }
            this.externallyManagedDestroyMethods.add(destroyMethod);
        }
    }

    public boolean isExternallyManagedDestroyMethod(String destroyMethod) {
        synchronized (this.postProcessingLock) {
            return (this.externallyManagedDestroyMethods != null &&
                    this.externallyManagedDestroyMethods.contains(destroyMethod));
        }
    }


    @Override
    public RootBeanDefinition cloneBeanDefinition() {
        return new RootBeanDefinition(this);
    }

    @Override
    public boolean equals(Object other) {
        return (this == other || (other instanceof RootBeanDefinition && super.equals(other)));
    }

    @Override
    public String toString() {
        return "Root bean: " + super.toString();
    }

}
